In dispute is what the CIA told Speaker Pelosi about severe interrogation methods, such as waterboarding. CIA officials say they told her these methods had been used against a detainee. She says they told her these methods had merely been approved for use.

Midday Thursday, Republican leader John Boehner called on Pelosi to produce evidence to back up her allegations: “The American people place their trust in our intelligence officials to keep them safe, and I think they deserve answers as quickly as possible.”

Later in the day, the House voted down party lines, 252 to 172, to derail a Republican resolution to set up a bipartisan congressional panel – two Democrats and two Republicans – to investigate Pelosi’s allegations.

After the vote, the Democrats went on the offensive. Majority leader Steny Hoyer noted that Republicans have themselves accused the CIA of misrepresenting facts.

As one example, he cited Republican leader Mr. Boehner, who on Dec. 9, 2007, said: “Either I don’t have confidence in what the intelligence community told me several months ago, or I don’t have confidence in what they’re telling me today."

He also noted a comment by Rep. Peter Hoekstra, the top Republican on the House Intelligence committee, who on Nov. 20, 2008, said that the intelligence community "covers up what it does and then lies to Congress."

“The Republican Party has been pursuing a policy of distraction,” Representative Hoyer said. It’s an attempt to divert attention from the Bush administration’s treatment of prisoners, he added; “treatment that, clearly, every American would abhor it if such treatment were visited upon our own soldiers and citizens."

Blasting the CIA was a common event on Capitol Hill in the mid-1970s, when sensational investigations on CIA misdeeds at home and abroad chaired by Sen. Frank Church (D) of Idaho led to the creation of a permanent intelligence oversight committees on Capitol Hill.

“What changed was the fact that we had so many Americans murdered in 2001,” says Rep. Barney Frank (D) of Massachusetts. “So there is now an element of, ‘Oh, the CIA protects us.' "

Commenting on Pelosi’s charges, he said: “There are two possibilities: One, that nobody in the CIA has ever misled the Congress – and I think that’s unlikely – or, two, that you should never say it even if it were true, and I think that’s wrong.”

Moreover, it’s not unusual for members attending the same intelligence briefing to come out with different views of what was said, suggests Rep. John Murtha (D) of Pennsylvania, who chairs the House Appropriations panel that oversees the CIA budget.

“It’s confusing to me what the CIA says in many cases," he says. "The thing is you have to know enough to ask the right question, and even then you may not get the right answer.”

"I know as much about defense as anyone in the country, and it is not easy,” he adds. “You go to a briefing, you listen to them, and you may interpret it differently than someone else.”

The outpouring of Democratic support was a clear signal that party lawmakers are mounting a defense of their speaker.